Air Shield on Turbofan Engines

With development of aviation for passengers, the number of passengers and airports is increasing. After the rapid raising of the amount of passenger jets, the probability to occur bird strike would raise at the same time.  

This idea came from a movie named Sully. The film follows Sullenberger's January 15, 2009 emergency landing of US Airways Flight 1549 on the Hudson River in New York City in which all 155 passengers and crew survived - most suffering only minor injuries - and the subsequent publicity and investigation. The cause of this accident was a bird strike that caused the aircraft to both engines to stall. The accident did not occur in the airspace of the airport with a bird-repellent device but over New York City. Thus, unless the aircraft could have driven away the birds by itself, pilots had no way to prevent the accident.

I'm curious that why there is no such equipment which has been applied on any airplanes, thought the world costs billions of dollars every year on repairing from bird strike. Therefore, I searched the Internet, including lab reports, engine manufacturer websites and patents, to generate this idea.